A frictionless pulley has the shape of a uniform solid disk of mass 2.3 kg and radius 10 cm. A 1.90 kg stone is attached to a very light wire that is wrappef around the rim of the pulley (the figure J, and the system is released from the rest.

What is the speed [in m/s} of the stone when the the pulley has 4.7 J of kinetic energy?

**The Solution**

given that

mass of solid disk is M = 2.3 kg

mass of stone is m= 1.90 kg.

and the radius of the solid disk is R = 10 cm= 0.1 m.

Kinetic energy KE = 4.70 J.

And it is released from the rest that mean the values of the initial speed, Kinetic energy and angular velocity are zeros.

so we will find the speed of stone when the pully has Kinetic energy 4.7 J.

The figure below shows the solution steps